1. Field of the Invention
The present invention relates to a structural improvement of a valve mechanism in a sliding exhaust brake provided halfway of an exhaust pipe generally in a large-sized automobile such as truck, bus or the like, blocking a passage of exhaust gas flowing in the exhaust pipe at the time of steep downward slope, thereby providing a braking effect to the automobile.
2. Description of the Prior Art
As exemplified in FIG. 7, a valve mechanism of a prior art exhaust brake of this kind is structured such that an exhaust pressure regulating hole (24) provided through the surface of a platelike valve member (23) installed in a reciprocating way within a housing of the body is slit in the cross direction, a block member (25) fixed near the nose of a piston rod (26) and engaging with the valve member (23) operates correlatively with an auxiliary valve member (27) with a liner (28) rectangular to the aforementioned slit to slide on the surface of the valve member (23) fitted loosely and so laid on the lower surface of the block member, and an exhaust passage is operated through pushing and lifting by impact and engagement on a side of the valve member (23) at a nose portion of the piston rod (26) and a side wall surface of the block member (25). Then, (29) denotes a small-diametral exhaust vent for prevention of overload to an engine side when the exhaust passage is kept close.
However, as a structure of the aforementioned auxiliary valve member, since restrictions are placed inevitably on a size of the exhaust pressure regulating hole (24) relatively to that of the valve member (23) in a limited space, a sufficient exhaust pressure drop is not obtainable in advance to opening, and the engaging construction by impact for operating the passage is capable of causing wear or rattle on a mutual contact portion, and an actuation repeated so frequently at the time of service may shorten a lifetime of products and thus deteriorate a long durability.